Agricultural harvesting machines, such as balers, are used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. In the case of hay, a mower-conditioner is typically used to cut and condition the crop material for windrow drying in the sun. In the case of straw, an agricultural combine discharges non-grain crop material from the rear of the combine defining the straw (such as wheat or oat straw) which is to be picked up by the baler. The cut crop material is typically raked and dried, and a baler, such as a large square baler or round baler, straddles the windrows and travels along the windrows to pick up the crop material and form it into bales.
On a large square baler, a pickup unit at the front of the baler gathers the cut and windrowed crop material from the ground. The pickup unit includes a pickup roll, and optionally may include other components such as side shields, stub augers, wind guard, etc.
A packer unit is used to move the crop material from the pickup unit to a duct or pre-compression chamber. The packer unit forms a wad of crop within the pre-compression chamber, which is then transferred to a main bale chamber. (For purposes of discussion, the charge of crop material within the pre-compression chamber will be termed a “wad”, and the charge of crop material after being compressed within the main bale chamber will be termed a “flake”). Typically such a packer unit includes packer tines or forks to move the crop material from the pickup unit into the pre-compression chamber. Instead of a packer unit it is also known to use a rotor cutter unit, which chops the crop material into smaller pieces.
A stuffer unit transfers the wad of crop material in charges from the pre-compression chamber to the main bale chamber. Typically such a stuffer unit includes stuffer forks which are used to move the wad of crop material from the pre-compression chamber to the main bale chamber, in sequence with the reciprocating action of a plunger within the main bale chamber.
In the main bale chamber, the plunger compresses the wad of crop material into flakes to form a bale and, at the same time, gradually advances the bale toward the outlet of the bale chamber. The plunger reciprocates, back and forth, toward and away from the discharge end of the baler. The plunger may include a number of rollers, which extend laterally outward from the sides of the plunger. The rollers on each side of the plunger are received within a respective plunger slot formed in the sidewalls of the bale chamber, with the plunger slots guiding the plunger during the reciprocating movements.
When enough flakes have been added and the bale reaches a full (or other predetermined) size, a number of knotters and needles are actuated which wrap and tie twine, cord or the like around the bale while it is still in the main bale chamber. The twine is carried to the knotters by the needles that pivot through the bale chamber to the knotters. The twine is grasped, cut and tied, and the formed baled is ejected out the back of the baler as a new bale is formed.
In EP1066747 a baler is disclosed having a sensor and timer operations, including a trip arm related to a stuffer mechanism that activates the sensor. However, the sensor is not for a knotter mechanism.
In EP2011385 it is disclosed that a blast of air can be delivered at the tip of the needles to dislodge crop material as they arrive at the knotters having passed through the bale chamber.
In U.S. Pat. No. 465,235 there is disclosed a monitoring system for detecting the malfunctioning of a knotting mechanism of a baler. However the system does not monitor or control multiple features.
In EP2803259 a tractor and baler combination is shown where a control unit is able to control the drive connection between the tractor and baler when a critical operating state of the pickup or knotting mechanism of the baler is detected.
What is needed in the art is an agricultural baler that can effectively monitor multiple functions of the knotting system in an efficient manner.